In the previous part of our Quality Engineering series, I discussed that the Process Failure Mode and Effects Analysis (PFMEA) is, in essence, a simple tool – a table with around 20 columns. However, using a tool doesn’t always guarantee good results. This particular tool, the PFMEA, takes its shape as a form, which must be filled out to get results you desire. Sometimes, your superior will need you to perform the PFMEA, and other times it’s the customer with the request. In either scenario, the PFMEA needs to be completed thoroughly, and with maximum effort, to avoid expensive external failure costs.
Unfortunately, most of the time, companies start on the PFMEA way too late, which is the first major mistake. Instead of organizations working against the deadline of, “We need to order this equipment for our new line”, they’re working toward, “Our customer wants this form filled out”.
When you’re ordering your new processing line, you’re buying a somewhat frozen design, layout, process sequence, and mistake-proofing system devised by your vendor. If you didn’t work with your equipment vendor closely enough, you only get their evaluation, which may not be relevant for your operators (the ones potentially making the mistakes). So, without analyzing the process prior to purchase, you’ve opted to use the trial-and-error method of quality improvement: you make errors, fix them, then account for why the errors were made in order to adjust the system.
Some customers have very stringent requirements and fast-paced, high-volume production of their own that has no time for employee errors, and the cost of these errors is often out of proportion to the cost of the product you’re supplying to them.
How to Improve Your PFMEA
Thoroughly analyzing your process before you rush into production is fundamental to maximizing your results from the PFMEA. Emphasis on thorough. This where PFMEAs are mis-used, and how they are poorly created, the most; they’re commonly not thorough enough, especially when accounting for missed failure modes. I should note that analysis doesn’t always have to be with PFMEA; anything with a thorough, robust analysis of risk would be useful. I just happen to know PFMEA the best.
Thoroughness is matter of process not structure. The PFMEA structure is simple: 20-plus columns. But what about the rows? This is where thorough comes in. All of the PFMEA training I’ve experienced talks about structure in detail. Most training provided excellent definitions of the columns, where to get the information, and showed several helpful examples of each. They all include the tables for rankings for Severity, Occurrence, and Detection, too. They also describe who should be on the teams (important), but surprisingly mentioned very little about being exhaustive and thorough.
Start from Scratch
So how do you create a PFMEA? Start from scratch. Working off a previous form is a mistake the automotive industry suffered from for the last 25 years. Copying previous, similar, but most importantly, inadequate PFMEAs is the best way incorrectly analyze your new process. Yes, there’s information to consider from the previous PFMEA you can use, but don’t start there. It’s critical to start fresh for every new process. Then, when your organization has acquired several PFMEAs over time, you can look to previous instances for reference. Think of it this way: if you build a new house on an old foundation, you’ll end up with the same leaks, cracked drywall, and stuck doors as your old house.
Remember, the key is to be thorough. Working on what’s changed is a good strategy once the quality of your PFMEAs rises and you have confidence in them, but there are still interactions, circumstances, and situations that you must account for unless you’re doing the exact same thing.
From my experience, most professionals have never seen a high-quality PFMEA, and haven’t seen one created well either. So for the next part in this series, I’ll be discussing why professionals loathe them and how we can turn this mindset around by improving our PFEMA processes. There’s real power behind this type of thorough analysis, and the benefits a PFMEA can bring to a manufacturing business are especially valuable during the planning stage – before any equipment or process is designed or purchased.